This invention is related to heat exchangers of the kind that include pipes or tubes extending between two tube plates, and with one fluid streaming inside the tubes and another outside the tubes. The tube package or heat exchanger core is surrounded by a shell.
One problem with a heat exchanger of this kind is that the tubes when heated will expand causing considerable tension in the tubes, tube plates, and the shell. This is sometimes enhanced further by the use of different materials for the tubes and shell. These tensions in turn will shorten the life span of the heat exchanger.
In order to diminish these tensions it is known to arrange the tubes with angular progression between the two plates. Slightly spirally or helical progressions are shown in the U.S. Pat. No. 1,655,086. The helical shape or angular progression will provide a resilience to core and the tension will be reduced. However these heat exchangers have a tendency to become rather expensive to manufacture due to the great number of steps and amount of manual labor necessary to produce each heat exchanger.
The object of the invention is to provide a heat exchanger with an angular progression for the tubes that can be manufactured simply and with a minimum amount of manual labor. It is also the object of the invention to provide a space efficient heat exchanger. Since heat exchangers with more or less straight tubes and tube plates at each end tend to be less space efficient than other types, and for many appliances they become unpractically long.